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.Dd May 17, 2025
.Dt SOCKETPAIR 2
.Os
.Sh NAME
.Nm socketpair
.Nd create a pair of connected sockets
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In sys/types.h
.In sys/socket.h
.Ft int
.Fn socketpair "int domain" "int type" "int protocol" "int *sv"
.Sh DESCRIPTION
The
.Fn socketpair
system call creates an unnamed pair of connected sockets in
the specified communications
.Fa domain ,
of the specified
.Fa type ,
and using the optionally specified
.Fa protocol .
The descriptors used in referencing the new sockets
are returned in
.Fa sv Ns [0]
and
.Fa sv Ns [1] .
The two sockets are indistinguishable.
.Pp
The
.Dv SOCK_CLOEXEC ,
.Dv SOCK_CLOFORK
and
.Dv SOCK_NONBLOCK
flags in the
.Fa type
argument apply to both descriptors.
.Sh RETURN VALUES
.Rv -std socketpair
.Sh ERRORS
The call succeeds unless:
.Bl -tag -width Er
.It Bq Er EMFILE
Too many descriptors are in use by this process.
.It Bq Er EAFNOSUPPORT
The specified address family is not supported on this machine.
.It Bq Er EPROTONOSUPPORT
The specified protocol is not supported on this machine.
.It Bq Er EOPNOTSUPP
The specified protocol does not support creation of socket pairs.
.It Bq Er EFAULT
The address
.Fa sv
does not specify a valid part of the
process address space.
.El
.Sh SEE ALSO
.Xr pipe 2 ,
.Xr read 2 ,
.Xr socket 2 ,
.Xr write 2
.Sh STANDARDS
The
.Fn socketpair
system call conforms to
.St -p1003.1-2001
and
.St -p1003.1-2008 .
.Sh HISTORY
The
.Fn socketpair
system call appeared in
.Bx 4.2 .
.Sh BUGS
This call is currently implemented only for the
.Ux
domain.
